On Thu, 08 Aug 2024 14:37:39 +0200, Marc Espie wrote:

> I've got several scripts that use mpv to display pictures.
>
> It used to be that I could ^Z and fg on those scripts without any issues.
>
> For a few weeks/months now, it seems to be broken. I have zero idea if
> this is an issue with mpv, ksh, or signal handling.
>
> I think mpv gets into another process group for whatever reason ?
>
> It still gets suspended, but TCONT doesn't do a thing.

I don't think there were any recent ksh changes that would account
for this.  You could try changing the scripts to use bash and see
if there is a behavior change.  When job control is enabled it is
normal for a command to be placed in its own process group.  But
for scripts, unless the scripts uses "set -m", I would expect the
command to have the same process group as the script itself.

There have been recent changes in the kernel related to signal
handling and stopped processes.  It's possible that something got
broken, but that would not change the process group a command runs
in.

It's also possible that this is a long-standing bug that is getting
triggered more often due to some of the syscall unlocking that has
happened.

 - todd